Improvement in duplex telegraphs



UNITED STATES PATENT OFFICE.

IMPROVEMENT lN DUPLEX TELEGRAPHS.

si.. it.. ti-.n tannin; par: .-f Lftms l'utt-ut No l I7,9l7. Intell Februari 24,1574;

June?? laA it known that l, 'l`nn.\t.\.- A. I'Ziusox, of .Yr-nark, in the eounty o( l'lssex and State of New Jersey, have invented ltnprmfements in ttrenits t'nr Duplex lilectrie I`ele.graplts, ot' whieh the following is a specification:

l'his invention is for enahlingthe operators at both stations to receive simultaneously, and that without the reeeivuginstrument being atleeted by the signals transmitted from the sante station. I aceomplish these objects by arranging the batteries, circuits, and magnets sothat the receiving portion of theinstrument will only respond to the pulsations from the distant instrument.

In the accompanying diagmm, the line a is connected, through the eleetromaguets b c d, to the key c, and the batteryfis divided, half being at each station, as usual. g is a rheostat, to prevent the current being shortcircuited, but always to maintain a connection of the line to the earth, even when the key e may be open. The batteries k and l are of equal power, and are connect-ed in the circuit Il in opposition to each other, and in that circuit is the sounder 1n, or other indicating-instru ment or call. The battery k is connected with the armature circuit-closer operated by the magnet c, and the batteryl with the armature circuit-closer of the magnet d. In the eireuit 3 is a rheostat, n, of suieient resistance to insure the electricity from the battery o passing through the sounder m when the circuit-close:- of I1 is operated. The instruments at both ends of the line are the same and the adjustments correspond.

The armatures ot' b c d are adjusted to dift'ereut tensions. Suppose, as an illustration, that the magnet d is operated by au electric energy of 50, the magnet c by an energy of300, and the magnet l by an energy of 150, and that :Application tiled the power o( the batteryfis ltltl, but the signal received from one station at the other is only represented by 5U. lf, now, theoperntor closes key 4', bolli the magnets l and e, by the power ol'f, respond, and make and break the circuits to the batteries l and lr, and therel is noaetion on the sounder m or the magnet l'. lf the operator at the distant station closes his key when the key c is closed, the fleet rie tension is increased by the increased energy represented by 50; hence the magnet l' responds by the joint current from both ends, and operates the sounder m by the battery o: but it" the key l. is open, the magnet l responds to the pulsation from the distant station and short-circuits the battery l, allowing the hat tery k to be unbalanced and to operate the sounder m. Thus the signal can he received from the distant station whether the key c is open or closed, and the operator can also hear the click of his own magnets e l without aetnating the sounder m.

y this arrangement the operators al both ends ot` the line can he receiving and sending over one wire, and the sounder or receiving-instrument is only operative from the dist-ant station, and it is operative as well when the key e is open as when it is closed, and vice versa.

I claim as my invention- The batteries l: l o and eircuits and circuitclosers of the eieetroanagnets b e d, in combination with the electro-magnetic sounder or call m and key c, the parts being adjusted to operate substantially in the manner specified.

Signed by me this 23d'day ol` April, A. I).

, THOS. A. EDISON. Witnesses:

Guo. T. ltNeuNx-zf, (uns. Il. Sutra. 

